We propose to use anti-idiotypic antisera and idiotypic antibodies to investigae the role of idiotype anti-idiotype interactions in the Ir gene controlled GAT immune response. Previous studies demonstrated that the anti-GAT antibodies of all mouse strains expressed a common set of idiotypic specificities, termed CGAT idiotype(s). Further, the GAT specific T suppressor factor(s), GAT-TsF, a T cell product with GAT binding activity, also exhibited CGAT idiotype. Our specific objectives are: (1) To study the fine idiotypic specificities of GAT-, GA-, and GT-TsF and to determine the presence of H- or L-chain specific idiotypic determinants on these TsF. These relate to the nature of TsF receptors. (2) To study whether GAT-TsF mediated suppression is idiotypic specific. (3) To generate idiotype specific T suppressor cells, Id-Ts, by the treatment of anti-idiotype or idiotype conjugated syngeneic spleen cells. (4) To study the idiotypic properties of GAT specific DTH and T helper cells and (5) To study the interaction of Id-Ts and DTH T cells and T helper cells. The manipulation of these systems and the mouse combinations chosen will allow us to understand the roles of H-2-linked Ir genes and Igh-linked V genes and their interrelationships in controlling the GAT immune response.